In the wire and cable industry, which includes optical fiber cable manufacture, an elongated strand material is moved along a manufacturing line where various operations are performed on the strand material. For example, a copper wire which has been drawn from copper rod is preheated, annealed and plastic insulating material extruded onto the wire. Thereafter, the insulated wire is cooled by water, and excess water is removed by an air-wipe device. Additional operations might include the application of a colorant material to an outer surface of the insulated wire, high-voltage testing, inspection and repair.
It is generally undesirable to stop an extruder or disrupt the continuous flow of optical fiber from a draw tower due to a problem that occurs further down the manufacturing line. Extruders might need to be dismantled and cleaned, or the fiber draw process restarted--both of which are time consuming. Nevertheless, there are times when the output needs to be slowed or discontinued to allow cutover from a full take-up reel to an empty one, or to correct some problem along the manufacturing line. These concerns are addressed by apparatus that is capable of storing a length of the elongated strand material such that the manufacturing line is not interrupted upstream or downstream from the problem. Such apparatus is frequently referred to as an accumulator whose job it is to buffer speed variations between input and output--even to the extent that it must provide output strand material when there is no input, and accumulate input strand material when there is no output.
One example of an accumulator is shown in U.S. Pat. No. 3,163,372 which comprises groups of sheaves. Without interrupting the flow of strand material at its input, the axes of the groups of sheaves are moved away from each other in order to slowdown or stop the flow of material at the output. And when there is no further need to have zero output, the axes of the groups of sheaves are moved toward each other. Although such an accumulator, frequently referred to as a "dancer" because of its rhythmic movements, has been used for many years in the wire and cable industry to facilitate cutover between reels, there are shortcomings associated with its use. For example, each loop of stored material requires a pair of sheaves and the volume of material which can be stored is severely limited. Consequently, the floor space required to store any significant volume of strand material is prohibitive.
What is needed, and what seemingly is not available in the art, is an apparatus for storing and delivering a large volume of moving strand material in a relatively small space. Furthermore, this apparatus should be uncomplicated, allow a controlled accumulation of material, and be capable of integration into a variety of operations along a manufacturing line that processes elongated strand material.